When I was a boy in the 1960s, my father had nine season tickets to the San Francisco 49ers, and on Sundays in the fall would often bring as many as seven of his 11 children to see the team play at Kezar Stadium. Kezar was at the southeast corner of Golden Gate Park, adjacent to the Haight-Ashbury District. In 1967, there was probably no greater side-by-side contrast of the diverging trends in American culture than between the people inside that stadium, watching a game played on grass, and the people outside the stadium, smoking grass. At the age...